In order to cool a coolant water (refrigerant) for an engine of a work vehicle such as a hydraulic excavator or a wheel loader, a radiator and a cooling fan for blowing a cooling air (outside air) to the radiator are mounted on the work vehicle. The cooling fan is driven by a hydraulic motor which is driven independently of the engine, and the cooling air can be sent to the radiator by rotating the cooling fan. In such a cooling fan, if the air blowing direction is one direction, dust is sent to the radiator together with the cooling air to cause clogging. Therefore, a cooling fan control device has been proposed in which the dust that has been trapped in the radiator during forward rotation is removed by a reverse flow of the cooling air generated by the reverse rotation by controlling the drive of the cooling fan in forward and reverse rotation (refer to Patent Literature 1).
The cooling fan control device disclosed in Patent Literature 1 has an automatic mode in which a rotational direction of the cooling fan is automatically switched at predetermined time intervals, and a manual mode in which the rotational direction of the cooling fan is switched at an arbitrary timing by an operator. An upper limit to the rotational speed of the engine is set only when the forward and reverse rotation of the cooling fan is controlled manually by the operator so that a large load is not exerted on the hydraulic motor, the valve, and so on configuring a hydraulic circuit.